Solis S5-GC40K40kW three-phase grid-tied string inverter, 4 MPPT

Overview

The S5-GC40K is the largest model of the Solis S5-GC(25-40)K three-phase string inverter series, rated 40kW with up to 44kVA of maximum output. Four MPP trackers with two strings each accept 32A per tracker between 200V and 1000V, and Solis recommends up to 60kW of PV, a 1.5 DC/AC ratio. Peak efficiency is 98.7% and European efficiency 98.3%. It shares the 647×629×252mm, 42.1kg housing of the 36kW model and needs an 80A AC protection device according to the manual.

• 25, 30, 33, 36 and 40kW, 3/N/PE 380/400V
• 3 MPPT (25–33kW) or 4 MPPT (36–40kW), 32A each
• 1100V max. input, 200–1000V MPPT range
• Max. efficiency up to 98.7%
• String monitoring and I-V curve scan
• IP66, fan cooling, LCD display

How it works

The S5-GC(25-40)K is a transformerless three-phase string inverter for grid-connected PV systems on commercial and agricultural roofs. The 25, 30 and 33kW models have three MPP trackers, the 36 and 40kW models four, each taking two strings and up to 32A, so roof areas with different orientations can be served by one inverter. The MPPT window runs from 200V to 1000V with a maximum input of 1100V.

Solis recommends a PV array of 1.5 times the rated power, for example 37.5kW on the 25kW model and 49.5kW on the 33kW model. Maximum AC output is 10% above the rated power. The grid connection is 3/N/PE at 220/380V or 230/400V, 50Hz or 60Hz, and night-time self-consumption is below 1W.

Key features

Each string is monitored, and the inverter can scan the I-V curve of the array to help locate faulty or shaded modules. A multi-peak scan keeps the tracker on the true power maximum under partial shading. AFCI 2.0 arc detection and night-time PID recovery are available as options, and DC and AC type II surge protection is built in.

With an optional three-phase smart meter, the inverter limits the power exported to the grid or records the building's consumption around the clock. The meter is installed either at the grid connection point or in the load branch, as described in the manual. Solis offers a direct-connection meter up to 80A and a version with 150A/5A CTs.

Installation and compatibility

The housing is IP66, measures 647×629×252mm and weighs 38.2kg (25–33kW) or 42.1kg (36–40kW); cooling is by intelligent fans. It is mounted vertically or tilted back by up to 15°, with 500mm between inverters and from the floor. The manual specifies AC protection of 50A for the 25kW, 63A for the 30kW and 33kW, and 80A for the 36kW and 40kW models.

The AC side uses OT ring terminals on copper cable of 10–35mm², with an integrated neutral connection point. For Italy, Solis publishes a CEI 0-21 declaration and certificate for the S5-GC(25-40)K; VDE-AR-N 4105, EN 50549-1 and EN 50549-2 certificates are also available.

Monitoring and settings

An LCD display with four buttons is used for local settings, including grid code, power limits and export management. RS485 is standard; remote monitoring through SolisCloud needs an optional Wi-Fi or GPRS data logging stick. Firmware of the display and control board can be updated, and an external Solis EPM unit can be used for multi-inverter export control.

Questions and answers